Fix: Add missing includes for std::back_inserter and std::atomic

Newer LLVM/libc++ versions (e.g. LLVM 23.1.3, llvm-mingw-20261006-ucrt) no longer transitively include <iterator> and <atomic>. This causes build failures in: modules/calib3d/src/stereo_geom.cpp, modules/gapi/include/opencv2/gapi/infer/ie.hpp (std::back_inserter), and modules/gapi/include/opencv2/gapi/gasync_context.hpp (std::atomic). Fixes build with modern LLVM/MinGW toolchains without CMake workarounds.

modules/calib3d/src/stereo_geom.cpp

@@ -3,6 +3,7 @@
 // of this distribution and at http://opencv.org/license.html
 
 #include "precomp.hpp"
+#include <iterator>
 
 namespace cv {
 

modules/gapi/include/opencv2/gapi/gasync_context.hpp

@@ -7,6 +7,8 @@
 #ifndef OPENCV_GAPI_GASYNC_CONTEXT_HPP
 #define OPENCV_GAPI_GASYNC_CONTEXT_HPP
 
+#include <atomic>
+
 #if !defined(GAPI_STANDALONE)
 #  include <opencv2/core/cvdef.h>
 #else   // Without OpenCV

modules/gapi/include/opencv2/gapi/infer/ie.hpp

@@ -11,6 +11,7 @@
 #include <unordered_set>
 #include <string>
 #include <array>
+#include <iterator>
 #include <tuple> // tuple, tuple_size
 #include <map>